Microsoft develops shape-shifting touchscreen

Microsoft this week filed a patent application covering a novel way to construct a "tactile" touchscreen – a display that uses technical tricks to convince users they are actually touching the ridges, bumps and textures of a displayed image.

Whereas previous screens produced only an illusion of texture, Microsoft proposes producing a real texture, using pixel-sized shape-memory plastic cells that can be ordered to protrude from the surface on command.

It's a new approach to the challenge, but not the first. Communications giant Nokia, Disney Research in Pittsburgh, Pennsylvania, and a Finnish firm called Senseg are all developing displays that use voltages of different frequencies, applied to a grid below the touchscreen, to trick our fingertips into experiencing a wide variety of touch sensations. They are known as vibrotactile displays.

They work well, but have limitations. For one thing, they can be noisy: some of the frequencies are in the audio range, so a buzz can be heard. Such problems may have prompted Microsoft to pursue a radically different approach.

UV switch

In US patent application 2010/0295820, published yesterday, Microsoft proposes using a layer of shape-memory plastic placed above a large touchscreen to distort the surface of the screen when different wavelengths of ultraviolet light strike the pixels from beneath.

Microsoft's named inventor, Erez Kikin-Gil at the firm's Redmond campus in Washington state, says in the patent that the idea is aimed at large table-sized computing displays such as the company's Surface, rather than phones or tablets.

A projector built into the Surface displays a computer image onto the table top from below. As the user touches it, infrared reflections from their fingertips are detected by cameras beneath the table and used to pinpoint the position of the finger and lend touchscreen capability.

In the patent, Microsoft proposes coating the display with a light-induced shape-memory polymer. This becomes hard and protruding when one wavelength of ultraviolet light is transmitted at a pixel, and soft when another wavelength hits it. By modulating these wavelengths, texture can be created, the patent claims.

However, Microsoft never comments on its plans for its patents and it is not yet known how feasible the idea is.

End of keypads

If it works it certainly would be welcome, says Patrick Baudisch, a display interaction expert at the University of Potsdam in Germany, who worked on the Surface in its early days.

"Creating well-defined bumps on a touch surface is in many ways the holy grail of text entry on touch devices because it would enable touch typing at much faster speeds than on touchscreens today," he says.

And if it could be used on smaller devices, it could spell the end of keypads on phones, he believes. "There would be no more reason for mobile keypads – they would simply be emulated when necessary. That could effect massive change in this field."

When this article was first posted, we mistakenly attributed the Disney Research work to researchers at Carnegie Mellon University.

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